SLUSF18B October   2023  – May 2026 BQ25638

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Description (continued)
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Power-On-Reset (POR)
      2. 7.3.2  Device Power Up from Battery
      3. 7.3.3  Device Power Up from Input Source
        1. 7.3.3.1 REGN LDO Power Up
        2. 7.3.3.2 Poor Source Qualification
        3. 7.3.3.3 Input Voltage Limit Threshold Setting (VINDPM Threshold)
        4. 7.3.3.4 Converter Power-Up
        5. 7.3.3.5 Input Current Optimizer (ICO)
        6. 7.3.3.6 Switching Frequency and Dithering Feature
      4. 7.3.4  Power Path Management
        1. 7.3.4.1 Narrow VDC Architecture
        2. 7.3.4.2 Dynamic Power Management
          1. 7.3.4.2.1 Input Current Limit on ILIM Pin
        3. 7.3.4.3 High Impedance (HIZ) Mode
      5. 7.3.5  Battery Charging Management
        1. 7.3.5.1 Autonomous Charging Cycle
        2. 7.3.5.2 Battery Charging Profile
        3. 7.3.5.3 Charging Termination
        4. 7.3.5.4 Thermistor Qualification
          1. 7.3.5.4.1 Advanced Temperature Profile in Charge Mode
          2. 7.3.5.4.2 TS Pin Thermistor Configuration
          3. 7.3.5.4.3 Cold/Hot Temperature Window in OTG Mode
          4. 7.3.5.4.4 JEITA Charge Rate Scaling
          5. 7.3.5.4.5 TS_BIAS Pin
        5. 7.3.5.5 Charging Safety Timers
      6. 7.3.6  USB On-The-Go (OTG)
        1. 7.3.6.1 Boost OTG Mode
      7. 7.3.7  Integrated 12-bit ADC for Monitoring
      8. 7.3.8  Status Outputs (INT , PG , STAT)
        1. 7.3.8.1 PG Pin Power Good Indicator
        2. 7.3.8.2 Charging Status Indicator (STAT)
        3. 7.3.8.3 Interrupt to Host (INT)
      9. 7.3.9  BATFET Control
        1. 7.3.9.1 Shutdown Mode
        2. 7.3.9.2 Ultra-Low Power Mode (ULPM)
        3. 7.3.9.3 System Power Reset
      10. 7.3.10 Protections
        1. 7.3.10.1 Voltage and Current Monitoring in Battery Only and HIZ Modes
          1. 7.3.10.1.1 Battery Overcurrent Protection
          2. 7.3.10.1.2 Battery Undervoltage Lockout
        2. 7.3.10.2 Voltage and Current Monitoring in Buck Mode
          1. 7.3.10.2.1 Input Overvoltage
          2. 7.3.10.2.2 System Overvoltage Protection (SYSOVP)
          3. 7.3.10.2.3 Forward Converter Cycle-by-Cycle Current Limit
          4. 7.3.10.2.4 System Short
          5. 7.3.10.2.5 Battery Overvoltage Protection (BATOVP)
          6. 7.3.10.2.6 Sleep and Poor Source Comparators
        3. 7.3.10.3 Voltage and Current Monitoring in Boost Mode
          1. 7.3.10.3.1 Boost Mode Overvoltage Protection
          2. 7.3.10.3.2 Boost Mode Duty Cycle Protection
          3. 7.3.10.3.3 Boost Mode PMID Undervoltage Protection
          4. 7.3.10.3.4 Boost Mode Battery Undervoltage
          5. 7.3.10.3.5 Boost Converter Cycle-by-Cycle Current Limit
          6. 7.3.10.3.6 Boost Mode SYS Short
        4. 7.3.10.4 Thermal Regulation and Thermal Shutdown
          1. 7.3.10.4.1 Thermal Protection in Buck Mode
          2. 7.3.10.4.2 Thermal Protection in Boost Mode
          3. 7.3.10.4.3 Thermal Protection in Battery-only Mode
    4. 7.4 Device Functional Modes
      1. 7.4.1 Host Mode and Default Mode
      2. 7.4.2 Register Bit Reset
    5. 7.5 Programming
      1. 7.5.1 Serial Interface
        1. 7.5.1.1 Data Validity
        2. 7.5.1.2 START and STOP Conditions
        3. 7.5.1.3 Byte Format
        4. 7.5.1.4 Acknowledge (ACK) and Not Acknowledge (NACK)
        5. 7.5.1.5 Target Address and Data Direction Bit
        6. 7.5.1.6 Single Write and Read
        7. 7.5.1.7 Multi-Write and Multi-Read
  9. 8 Register Maps
    1. 8.1 BQ25638 Registers
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Inductor Selection
        2. 9.2.2.2 Input Capacitor
        3. 9.2.2.3 Output Capacitor
      3. 9.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Third-Party Products Disclaimer
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information
    1.     PACKAGE OPTION ADDENDUM
    2. 12.1 Tape and Reel Information
    3. 12.2 Mechanical Data

7.3.2 Device Power Up from Battery

If only a battery is present and the voltage is above depletion threshold (VBAT_UVLOZ), BQ25638 performs a power-on reset, then turns on BATFET to connect the battery to system. The REGN stays off to minimize the quiescent current. The low RDSON of the BATFET and the low quiescent current on BAT minimize the conduction loss and maximize the battery run time.